The emerging graphene-based material, an atomic layer of aromatic carbon atoms with exceptional electronic and optical properties, has offered unprecedented prospects for developing flat two-dimensional displaying systems. Here, we show that reduced graphene oxide enabled write-once holograms for wide-angle and full-colour three-dimensional images. This is achieved through the discovery of subwavelength-scale multilevel optical index modulation of athermally reduced graphene oxides by a single femtosecond pulsed beam. This new feature allows for static three-dimensional holographic images with a wide viewing angle up to 52 degrees. In addition, the spectrally flat optical index modulation in reduced graphene oxides enables wavelength-multiplexed holograms for full-colour images. The large and polarization-insensitive phase modulation over π in reduced graphene oxide composites enables to restore vectorial wavefronts of polarization discernible images through the vectorial diffraction of a reconstruction beam. Therefore, our technique can be leveraged to achieve compact and versatile holographic components for controlling light.

Different morphologies ceria (nanocubes, nanorods and nanoparticles) were synthesized and exhibited significant support-morphology-dependent catalytic activity towards ammonia synthesis.

One-way-propagating broadly tunable terahertz plasmonic waveguide at a subwavelength scale is proposed based on a metal-dielectric-semiconductor structure. Unlike other one-way plasmonic devices that are based on interference effects of surface plasmons, the proposed one-way device is based on nonreciprocal surface magneto plasmons under an external magnetic field. Theoretical and simulation results demonstrate that the one-way-propagating frequency band can be broadly tuned by the external magnetic fields. The proposed concept can be used to realize various high performance tunable plasmonic devices such as isolators, switches and splitters for ultracompact integrated plasmonic circuits.

Tungsten-doped mesoporous KIT-6 (W-KIT-6), mesoporous silica supported WO 3 /KIT-6, and traditional silica supported WO 3 /SiO 2 catalysts have been successfully synthesized and tested for catalytic metathesis of 1-butene and ethene to propene. The resultant materials were comprehensively characterized by XRD, BET, TEM, UV−DRS, IR, XPS, H 2 -TPR, and TGA. For W-KIT-6 catalysts, high concentration of W 5+ species by XPS and the difficulty of reduction of W species by TPR suggested the incorporation of W species into the KIT-6 framework. The studies of smallangle XRD, BET, and TEM illustrated that the 3D ordered mesoporous structure and their high surface area of KIT-6 were maintained in W-KIT-6. The doped W-KIT-6 illustrated superior catalytic performance to the supported WO 3 /KIT-6 and WO 3 /SiO 2 catalysts. The origin of catalytic performance enhancement for W-KIT-6 was preliminarily discussed and was assigned to the incorporation of W species into KIT-6 framework. This study demonstrated the influence of neighboring environment of active components on catalytic performance and was helpful to design metathesis catalysts.

We propose and numerically analyze a plasmonic Bragg reflector formed in a graphene waveguide. The results show that the graphene plasmonic Bragg reflector can produce a broadband stopband that can be tuned over a wide wavelength range by a small change in the Fermi energy level of graphene. By introducing a defect into the Bragg reflector, we can achieve a Fabry-Perot-like microcavity with a quality factor of 50 for the defect resonance mode formed in the stopband. The proposed Bragg reflector could be used as a broadband ultrafast tunable integrated filter and a broadband modulator. In addition, the defect microcavity may find applications in graphene-based resonators.

Metasurfaces have become a new photonic structure for providing potential applications to develop integrated devices with small thickness, because they can introduce an abrupt phase change by arrays of scatterers. To be applied more widely, active metasurface devices are highly desired. Here, a tunable terahertz meta-lens whose focal length is able to be electrically tuned by ∼4.45λ is demonstrated experimentally. The lens consists of a metallic metasurface and a monolayer graphene. Due to the dependence of the abrupt phase change of the metasurface on the graphene chemical potential, which can be modulated using an applied gate voltage, the focal length is changed from 10.46 to 12.24 mm when the gate voltage increases from 0 to 2.0 V. Experimental results are in good agreement with the theoretical hypothesis. This type of electrically controlled meta-lens could widen the application of terahertz technology.

Due to their promising properties, surface magneto plasmons have attracted great interests in the field of plasmonics recently. Apart from flexible modulation of the plasmonic properties by an external magnetic field, surface magneto plasmons also promise nonreciprocal effect and multi-bands of propagation, which can be applied into the design of integrated plasmonic devices for biosensing and telecommunication applications. In the visible frequencies, because it demands extremely strong magnetic fields for the manipulation of metallic plasmonic materials, nano-devices consisting of metals and magnetic materials based on surface magneto plasmon are difficult to be realized due to the challenges in device fabrication and high losses. In the infrared frequencies, highly-doped semiconductors can replace metals, owning to the lower incident wave frequencies and lower plasma frequencies. The required magnetic field is also low, which makes the tunable devices based on surface magneto plasmons more practically to be realized. Furthermore, a promising 2D material-graphene shows great potential in infrared magnetic plasmonics. In this paper, we review the magneto plasmonics in the infrared frequencies with a focus on device designs and applications. We investigate surface magneto plasmons propagating in different structures, including plane surface structures and slot waveguides. Based on the fundamental investigation and theoretical studies, we illustrate various magneto plasmonic micro/ nano devices in the infrared, such as tunable waveguides, filters, and beam-splitters. Novel plasmonic devices such as one-way waveguides and broad-band waveguides are also introduced.

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